Electronic excitation of C6H6 by positron impact

Experiments on electronic excitation of molecules using positron as incident particle have shown much larger cross sections than in the electron scattering case. The comprehension of these inelastic processes represent a great challenge and only few studies on electronic excitation of molecules are discussed in the literature. For example, for the C6H6 molecule experimental and theoretical calculations are not in a very advanced state same for electron scattering case (Benzene represent a simplest aromatic hydrocarbon and very important chemical compound due to its role as a key precursor in process pharmaceutical). Recent experiments on electronic excitation of C6H6 (1B1u, and 1E1u electronic states) using electron as incident particle are available by Kato et al (J.Chem.Phys.134 134308(2011)). Motivated by their experiments we have taken up the task to investigate the same electronic excitation of C6H6 using positron as incident particle. For the first time, integral cross sections in e+ - C6H6 (1B1u, and 1E1u electronic states) using the scaling Born positron (SBP) approach are reported and in the absence of the experimental data and developments theoretical, comparisons are made with analogous electron scattering.Keywords: Born, positron, scaling

Inelastic Processes in Copper-Hydrogen Collisions Including Fine Structure Effects

Inelastic processes in low-energy Cu + H and Cu+ + H− collisions, such as mutual neutralization, ion-pair formation, excitation, and de-excitation, 306 partial processes in total, are investigated taking fine structure effects into account. We use the asymptotic approach to model the adiabatic potentials and adapt a recently proposed method to include the copper fine structure. The nuclear dynamics is performed by making use of the multichannel analytical approach and the Landau-Zener model. The rate coefficients are calculated for the temperature range 1′000 − 10′000 K. The largest rate coefficient is obtained for the mutual neutralization process Cu+ + H− → Cu(3d105s 2S1/2) + H with a value of 3.81 × 10−8 cm3/s at a temperature of 6′000 K. The next lower rate coefficients with values below 10−8 cm3/s correspond to the partial processes of mutual neutralization ${\rm Cu}^{+} + {\rm H}^- \rightarrow {\rm Cu}(3d^{10}5p~^2P^{\circ }_{3/2, 1/2}) + {\rm H}$, Cu+ + H− → Cu(3d104d 2D3/2, 5/2) + H, and the de-excitation process ${\rm Cu}(3d^{10}4p~^2P^{\circ }_{1/2}) + {\rm H} \rightarrow {\rm Cu}(3d^{9}4s^2~^2D^{\circ }_{3/2, 5/2}) + {\rm H}$. It is shown that the practice to redistribute LS-coupling rate coefficients among fine structure sublevels can give rates which deviate significantly from those calculated in the JJ-coupling scheme, that is, with account for the fine structure effects.

Neutron pick-up reactions in 18O (10 MeV/nucleon) + Ta

The availability of new radioactive ion beams has broadened the study of nuclear reactions and nuclear structure. The main mechanism to produce the secondary beams is the fragmentation of the projectile. An alternative method for the production of the exotic nuclei is the multinucleon transfer. We measured production cross section for the B, C, N and O isotopes in the reaction 18O + Ta and the beam energy at 10 MeV/nucleon. The cross-sections were obtained by integrating the momentum distributions of the isotopes. It was shown that in deep inelastic processes the production yields of different isotopes could be well described using statistical models and could also be explained by the Qgg-systematic.

Cobalt-Hydrogen Atomic and Ionic Collisional Data

Rate coefficients for inelastic processes in low-energy Co + H, Co + + H − , Co + + H , and Co 2 + + H − collisions are estimated using the quantum simplified model. Considerations include 44 triplet and 55 quintet molecular states of CoH, as well as 91 molecular states of CoH + . The estimations provide the rate coefficients for the 4862 partial processes (mutual neutralization, ion-pair formation, excitation, and de-excitation) in the neutral CoH system, and for the 8190 partial processes in the ionized CoH + system, 13 , 052 processes in total. At T = 6000 K, the rate coefficients with the largest values around 6 × 10 − 8 cm 3 s − 1 correspond to the mutual neutralization processes into the Co ( e 2 F ) + H and Co + ( g 5 F ) + H final channels in the neutral and ionized systems, respectively. Among the excitation and de-excitation processes in Co + H and in Co + + H collisions, at T = 6000 K, the largest rate coefficients have values around 7 × 10 − 9 cm 3 s − 1 and correspond to the processes Co ( y 2 S ∘ ) + H → Co ( e 2 F ; v 4 D ∘ ) + H and Co + ( h 3 P ) + H → Co + ( g 3 P ; g 5 P ; g 5 F ) + H , respectively. The calculations single out inelastic processes important for non-local thermodynamic equilibrium (NLTE) modelling of Co I and Co II spectra in stellar atmospheres. The test NLTE calculations are carried out, and it is found that the new collision rates have a strong effect on the line formation and NLTE abundance corrections.